Centrifugal sludge pump



June 10, 1941.

K. HARTMAN ,y CENTRIFUGAL SLUDGE PUMP 2 Sheets-Sheet 2 Filed Feb. 1s, 1959 Patented June 1 0, 1941.

cEN'rmrUGAL s LunGE rum Knute Hartman, Aurora, Ill., assignor to The American Well Works, Aurora, Ill., a corporationA of Illinois Application February 13, 1939, serial No. 256,117 12 claims. (ci. 10a-111) The principal object of this invention is to pro..-

vide a pump for handling such things as primary sludge that will not be clogged by the various solids commonly found therein, including stringy and rubbery materials. Generally speaking, this object is obtained by using an impeller with a spiral blade having a cutting edge at its fore side cooperating with a'cutting edge, or cutting edges at the suctionside of the pumpcasing. Further objects and advantages of the invention will appear as the description is read in connection with the accompanying drawings of the preferred embodiment, in which Fig. 1 is aldiagrammatic side elevation of the pump connected in a sewage treatment system;

Fig. 2 is a vertical longitudinal section through the pump;

Fig. 3 is a'perspective view oi the suction side of the casing illustrated as a suction cover and cutting ring;

Fig. '4 is a perspective view of the impelier;

Figs. 5 and 6 are transverse vertical sections taken as indicated by the broken line and arrows 5-5 and 6-6 on Fig. 2;

Fig. 'lis a vertical transverse section on the line 1-1 of Fig. 2; Figs.- 8 and9 are `sections taken on the vlines 8--8 and 9-9 of Fig. 6. A But these specific illustrations and the correspending description .are used for the purpose of illustration only and are not intended to place unnecessary limitations on the claims.

In Fig. l, the pump generally indicated by l0, isshown connected with piping II, leading from primary settlingtanks of a sewage system and piping I2 leading to' adigester, or such like. And in this view the power to drive the pumpisfurnished bya motor I3.

Turning to Fig. 2, it will be seen that the pump includes a base casting i4 finished to receive ball bearings I5 and I6, for the impeller shaft I1, which is adjustable lengthwise by 'a threaded sleeve I8.

At the left in Fig. 2, the casting I4 is iinished'to ,cooperate with a pump casing, including a shell 26, where it passes through the stumng box. At the left end of the cylindrical portion 23 the back,

or `stulng box cover takes the form of a dished position. 55

-disk 21, terminating ln a flange 28, received in a counterbore 29 in the casting I4, where it is held by Ithe adjacent portion of the shell I9.

The'suctlon cover plate iscored out at Iii and has a peripheral flange 3| fitted 'to the outside of the shell t9. The suction cover plate also has an eccentric bore 32, for a. cutting ring 33, having a ila-118e 8 4 held in a counteibore 35 by the flange 36 onthe suction nozzle 31, secured to the left` side of the pump by bolts 38. r

The impeller (see Figs. 2 and 4) includes a hub 39, threadedto the left end of the shaft I1 at 40, a dished shroud 4I on the left face of which is a single spiral blade 42, developing from a central eye 48, through outwardly divergingconvolutions, to the periphery -of the impeller at '44, and it will be noted that the blade grows deeper. or wider, as it extends outwardly from the eye ,43.

The outer, or what will be called the fore side, of the blade, is provided with a cutting edge 46 at the left corner in Figs. 2 and 4, which is preferably made by welding Stellite, or some similar hard alloy 41 on the corner and grinding it sharp.

vThis cutting edge cooperates with a stationary cutting edge, or cutting edges on the suction side of the pump casing. As shown, the nrst of these is at the inner corner 49 of the cutting ring 33, and others of which are shown as the corners formed by inclined grooves 50, made partly in the suction cover plate `2| and partly in the cutting ring. 'I'hese cutting edges, or at least the edge of the ring 33, are also formed by welding on Stellite, or

[some equivalent alloy, and grinding them sharp.

at 44. It will be observed that in addition to such shearing function as they may perform, the grooves 50 lie at a steep angle with respect to the blade and hence will cooperate therewith to force to the periphery any solid particles which might otherwise jam between the blade and the cover 1I.

With this arrangement the resulting shears can be adjusted by means of thethreaded sleeve `II to provide just the sort of shearing action necessary to cut all entrained solid matter into small particles in passing through the pump, thereby preventing any clogging.

It will be observed that the ring 33, together with the cutting edge 46, form what might be called a cutting trap In that any'material which is being sheared by them will not escape-by being slid along-the cutting edges to anon-shearing lvFig. 5' and consider some material at the inter- Thus.' if we start with the parts inl section of the spiral blade and the ring, it might be possible that this material would be slid along the edge o! the ring for a short distance. However, asit approaches the bottom of the ring, as seen in Fig. 5, the cooperating portions of the ring and the spiral blade would so closely Kapproach parallelism that the material would not be slid farther but would be sheared. As a matter of fact, the present structure forms an even more reliable trap by virtue of the fact that, even if the material was slid at this point, it would shortly thereafter reach a point where turn of the ring 33.

'I'he right, or back side of the impeller shroud Si is equipped with severalfvanes i, which serve as an auxiliary impeller to put a slight suction on the stuiiing box and prevent any solid matter from working downh between the back of the impeller and the stuffing box cover.

The suction opening 52 is tapered through the -suction nozzle 31 and the cutting ring 33' (Fig. 2)

and the discharge opening 53 (Fig. 6) is tapered in thereverse way -through the periphery of the shell I9. By preference these openings are not less than four inches for a pump having the impeller 9H inches outside diameter and the height of the blade varying from 1/2" to 11/2" at the periphery. In such a pump, grooves 50,-

1A" wide and 1A," deep, 30 to the radius have `been found eminently satisfactory.

Preferably nickel chromium iron is used for 1 the parts of the casing except the cutting ring,

which should be made of one percent (1%) manganese steel, .or the equivalent. The impeller should be made of the same material as the cutting ring, or the equivalent.

The suction nozzle 31 is `provided with a large hand .hole cover 54 (Figs. 2 and 7) conforming to the shape of the suction opening at the inner side and held in place by a screw clamp 55, en-

.cuity. The Stellite cutting edges have a hardness of 700" Brinell.

In applying the invention, those skilled in the art will choose forms and materials and make designs suited to conditions.

I claim as my invention:

1. In a pump, an impeller including a shroud with a spiral blade thereon having a cutting edge at its fore side and a casing enclosing the impeller including a lsuction cover having an opening eccentric to the impeller axis, one point of the opening approximately coinciding with the axis of the impeller to prevent material from .straddling the axial end of the impeller; the

suction' cover and opening forming a suction passage which is substantially unobstructed other than by the blade, and a substantial'peripheral and generally arcuate portion of the opening forming a cutting edge cooperating with the cutting edge of the spiral blade.

it could not slide at all because ofV the inward 2. In a pump, an impeller including a shroud with a spiral made thereon having a' cutting edge at its fore side and a casing enclosing the impeller including a suction cover having an inlet,

the edges of which are in shearing relation with the blade, the cover lying substantially in contact with the blade throughout most of the area of the inner face of the cover and having widely spaced outwardly directed grooves therein disposed to form a wide angle with the blade and extending approximately from the inlet to the periphery of the impeller, the edges of the grooves cooperating with the cutting'edge of the blade.

3. In a pump, an impeller including a shroud with spiral blade means thereon and a casing enclosing the impeller and having a suction cover having a suction inlet adjacent to the impeller and sufliciently eccentric with respect to the axis thereof to prevent solid objects catching at the axis of the impeller, and having at least a substantial peripheral part of its edge cooperating with the blade means forming a cutting edge, the blade means comprising not over two blades traversing the suction inlet, each blade cooperating with the cutting edge. f

4. In a pump, an impeller including a shroud with a spiral blade thereon having a cutting edge at its foreside anda casing enclosing the inipeller. including a suction cover having a sta tionary cutting edge, two spaced portions of which vare crossed simultaneously by a portion of fthe cutting edge of the blade rotating as one arm about the axis before said cutting edge of the blade crosses the intermediate portion of the stationary cutting edge; said edges cooperating to cut solid particles in the pumped fluid.

5. In a pump, an impeller including a shroud with a blade thereon having a cutting edge at its foreside and a casing enclosing the impeller including a suction cover having a stationary cut` ting edge, two .spaced portions of which `are crossed simultaneously -by a portion ofthe cutting edge of the blade rotating as one arm about the axis before said cutting edge of the blade crosses the intermediate portion of the stationary cutting edge; said edges cooperating to cut solid particles in the pumped fluid.

6. In a pump, an impeller including a shroud with a spiral blade thereon having a cutting edge at its foreside and a casing 'enclosing theimpeller including a suction cover having a suction opening formed by a cutting ring cooperating' with the cutting edge of the blade and eccentric to the impeller axis; a portion of the blade which cooperates with a part of the ring remote from the axis being approximately parallel with that part.

.7. In a pump, an impeller including a shroud with a blade thereon having a cutting edge at` its foreside and a casing enclosing the impeller includingfea suction cover having Aa. suction opening formed by a cutting ring with a substantial length of the ring forming a cutting edge cooperating with the edge of the blade; the axisof the impeller -being approximately at least as far from the center of said ring as the edge. of the ring.

8. In a pump, an impeller including a shroud with a spiral blade thereon having a cutting edgev at its foreside and a casing enclosing the impeller and having an outlet at the periphery of the impeller, including a shell and a suction cover adjacent to .the shroud having a suction inlet eccentric to -the impeller axis and defined at least in part by a stationary cutting'edge cooperating with the cutting edge of the impeller,' the stationary' cutting edge having at least its v 2,245,035 portion last crossedby the blade approximatelyy parallel with the portion of rthe cutting edge of the blade cooperating therewith and of such 'disposition and extent that any solidpparticles engaged between the blades will not be wiped along and oiI of the cutting edges. j

9. In a pump, an impeller including a shroud with a. spiral blade thereon having a cutting edgeat its foreside and a casing enclosing the impellex` including a shell and a suction 'cover adjacent to the shroud having a suction inlet eccentric to the impeller axis and a stationary cuttingedge cooperating with the cutting edge of the impeller, the stationary cutting edge having a portion which is approximately parallel with the portion oi the cutting edge of the blade cooperating therewith, and having another portion crossed by the blade just before it crosses fthe 1 lirst-namedportion and which is at a greater angle to the blade but slopes toward the ilrstnamed portion so that any movement of mate-g rial along the said another portion will be toward the mst-named portion.

10. In a pump, an impeller including a shroud,

with a spiral blade thereon having a cutting edge at its foreside and a casing enclosing the impeller including a shell and a suction cover adjacent to the shroud having a suction inlet eccentric to the impeller axis and a stationary cutting edge cooperating with the cutting edge of the impeller along the lentire portion oi' the blade which is at times exposed to the inlet; the cutting edge of the cover having two spaced portions thereof crossed simultaneously by a portion of theblade rotating as one arm labout the axis of the blade before the blade crosses the intermediate portion thereof.

11. In a pump, an impeller including a shroud with a blade thereon having a cutting edge at its foreside and a casing enclosing the impeller including a suction cover having a suction open-y ing and a stationary cutting edge adjacent the opening, two spaced portions of which stationary cutting edge are crossed simultaneously by a por- .tion of the cutting edge of the blade'rotating as one Aarm about the axis before said cutting edge 'of the blade crosses the intermediate portion of the stationary 4cutting edge; said edges cooperating to out solid particles in the pumped A iiuid," and said cover also having grooves therein disposed to form a wide angle with the blade 1 and extending approximately from the inlet to the periphery of the impeller, the edges of they grooves cooperating with the cutting edge of the blade to sweep toward the periphery any material jammed between the blade and the cover.

KNUTE HARTMAN. 

